A controller can include a signal generator configured to provide an input signal to a modulator. The controller can be configured to generate a modulator compensation parameter in response to a modulated feedback signal corresponding to an output of the modulator. The controller can also be configured to generate a power amplifier predistortion signal in response to an amplified feedback signal corresponding to an output of a power amplifier coupled to the modulator.
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1. A controller comprising: a signal generator configured to provide an input signal to a modulator; wherein the controller is configured to: generate a modulator compensation parameter in response to a modulated feedback signal corresponding to an output signal of the modulator, the modulated feedback signal being a portion of the output signal of the modulator and being coupled to the controller; and generate a power amplifier predistortion signal in response to an amplified feedback signal corresponding to an output signal of a power amplifier, the power amplifier coupled to the modulator and configured to receive the output signal of the modulator, the amplified feedback signal being a portion of the output signal of the power amplifier and being coupled to the controller, wherein the modulated feedback signal is different from the amplified feedback signal.
A controller manages signal transmission by adjusting for imperfections in both a modulator and a power amplifier. It generates an input signal for the modulator. It then calculates a compensation parameter based on a feedback signal from the modulator's output. Separately, it generates a predistortion signal based on a feedback signal from the power amplifier's output. The modulator compensation parameter corrects errors introduced by the modulator, while the power amplifier predistortion signal corrects errors introduced by the power amplifier. These two feedback signals are distinct, allowing independent correction of each component.
2. The controller of claim 1 , wherein the controller is further configured to subtract the modulated feedback signal from the amplified feedback signal to form a power amplifier feedback signal.
The controller described in claim 1 further improves power amplifier correction by subtracting the feedback signal from the modulator's output from the feedback signal from the power amplifier's output. This subtraction creates a dedicated power amplifier feedback signal, isolating the power amplifier's distortion characteristics from the modulator's characteristics, allowing for more accurate predistortion signal generation.
3. The controller of claim 2 , wherein the controller is further configured to store the modulated feedback signal in a memory.
The controller described in claim 1 and claim 2 includes memory to store the feedback signal from the modulator's output. Storing the modulator output signal allows the controller to analyze it separately, compare it with later modulator outputs, and potentially use historical data to improve modulator compensation parameter calculation and stability of compensation over time.
4. The controller of claim 1 , wherein the controller is further configured to analyze the modulated feedback signal to determine an operational characteristic of the modulator.
The controller described in claim 1 analyzes the feedback signal from the modulator's output to determine how the modulator is performing. This analysis could involve measuring signal characteristics like frequency response, amplitude, or phase to assess the modulator's operational status. The controller uses this information to dynamically adjust the modulator compensation parameter to optimize performance.
5. The controller of claim 4 , wherein the operational characteristic of the modulator characterizes an imbalance induced by the modulator.
The controller described in claim 1 and claim 4 specifically analyzes the feedback signal from the modulator's output to detect and quantify imbalances introduced by the modulator. This is particularly useful for detecting I/Q imbalance, where the in-phase (I) and quadrature (Q) components of the signal are not perfectly balanced. Correcting I/Q imbalance improves signal fidelity and reduces unwanted signal components.
6. The controller of claim 1 , wherein the controller is further configured to analyze the amplified feedback signal to determine an operational characteristic of the power amplifier.
The controller described in claim 1 analyzes the feedback signal from the power amplifier's output to determine how the power amplifier is performing. This involves examining the signal characteristics after amplification to identify any distortion, non-linearity, or other performance issues introduced by the power amplifier. This analysis helps the controller generate a more effective power amplifier predistortion signal.
7. The controller of claim 6 , wherein the operational characteristic of the power amplifier comprises at least one of a gain and a phase characteristic of the power amplifier.
The controller described in claim 1 and claim 6 analyzes the feedback signal from the power amplifier's output to measure either the gain, the phase characteristics, or both. Monitoring the amplifier's gain and phase provides critical information about its operational state and how it is altering the signal. Deviations from expected gain or phase response are used to adjust the power amplifier predistortion signal.
8. The controller of claim 1 , wherein the controller is further configured to control a switch that selects between the modulated feedback signal and the amplified feedback signal for coupling to the controller.
The controller described in claim 1 uses a switch to select which feedback signal (modulator output or power amplifier output) is sent to the controller for analysis. This allows the controller to focus on either modulator or power amplifier characteristics at different times, potentially reducing processing load or enabling different optimization strategies.
9. The controller of claim 1 , wherein an operational characteristic of the input signal is changed based on at least one of: the modulator compensation parameter and the power amplifier predistortion signal.
The controller described in claim 1 modifies the characteristics of the input signal based on either the modulator compensation parameter, the power amplifier predistortion signal, or both. This adjustment pre-corrects the signal before it enters the modulator and power amplifier, compensating for their known imperfections. This leads to a cleaner, more accurate output signal from the overall system.
10. A system comprising: a modulator comprising an input and an output, the modulator configured to generate a modulated signal at its output in response to an input signal at its input, the input signal provided by a controller; a power amplifier comprising an input and an output, the power amplifier configured to amplify the modulated signal at its input to provide an amplified signal at its output; and a switch comprising: a first input port coupled to the output of the modulator, a second input port coupled to the output of the power amplifier, and an output port coupled to the controller for providing a feedback signal corresponding to at least one of: the output of the modulator and the output of the power amplifier.
A signal transmission system consists of a modulator, a power amplifier, and a switch. The modulator generates a modulated signal based on an input from a controller. The power amplifier amplifies the modulated signal. The switch selects either the modulator's output signal or the power amplifier's output signal and sends it back to the controller as a feedback signal. This feedback allows the controller to monitor and correct for any signal degradation introduced by the modulator and power amplifier.
11. The system of claim 10 , further comprising: a digital predistortion (DPD) feedback circuit configured to receive the feedback signal from the switch, the DPD feedback circuit being configured to provide a DPD output feedback signal to the controller.
The signal transmission system described in claim 10 includes a digital predistortion (DPD) feedback circuit. This circuit receives the feedback signal from the switch and processes it to provide a digital feedback signal to the controller. The DPD feedback circuit prepares the feedback signal for digital processing and analysis by the controller, enabling precise correction of signal impairments.
12. The system of claim 11 , wherein the DPD feedback circuit comprises: a mixer configured to generate a mixer output signal, the mixer output signal being generated by substantially removing a carrier signal from the feedback signal; and an analog to digital converter (ADC) configured to generate the DPD output feedback signal by converting the mixer output signal into a digital feedback signal, wherein the digital feedback signal is provided to the controller.
The DPD feedback circuit described in claim 11 consists of a mixer and an Analog-to-Digital Converter (ADC). The mixer removes the carrier frequency from the feedback signal, simplifying the signal processing. The ADC then converts the mixer's output signal into a digital format that the controller can use for analysis and adjustment of the input signal to the modulator.
13. The system of claim 10 , further comprising: the controller configured to: generate a modulator compensation parameter for the modulator and a power amplifier predistortion signal for the power amplifier; and provide the input signal to the modulator, wherein an operational characteristic of the input signal is changed based on at least one of: the modulator compensation parameter and the power amplifier predistortion signal.
The signal transmission system described in claim 10 has a controller that generates both a modulator compensation parameter and a power amplifier predistortion signal. The controller also provides the input signal to the modulator. The characteristics of this input signal are modified based on the modulator compensation parameter and/or the power amplifier predistortion signal to counteract the imperfections of the modulator and power amplifier, ultimately improving the quality of the output signal.
14. The system of claim 13 , wherein the modulator comprises a quadrature amplitude modulation (QAM) channel, and the modulator compensation parameter is employed to change an operational characteristic of the input signal to compensate for an I/Q imbalance induced by the QAM channel.
In the signal transmission system described in claim 13, the modulator is a Quadrature Amplitude Modulation (QAM) channel. The modulator compensation parameter is specifically used to correct for I/Q imbalance (unequal amplitude and phase of I and Q signals) introduced by the QAM modulator. By pre-correcting for this imbalance, the overall signal quality is improved.
15. The system of claim 14 , further comprising an output circuit configured to propagate a radio frequency (RF) signal in response to the amplified signal.
The signal transmission system described in claim 14 incorporates an output circuit that propagates a Radio Frequency (RF) signal based on the amplified signal from the power amplifier. This output circuit effectively transmits the corrected and amplified signal wirelessly, making the system suitable for applications such as wireless communication.
16. A cellular network basestation comprising the system of claim 15 , wherein the cellular network basestation is configured to provide data to the controller, wherein the input signal is based on the data.
The signal transmission system described in claim 15 forms part of a cellular network basestation. This basestation is responsible for transmitting and receiving wireless signals. The basestation provides data to the controller, and this data forms the basis for the input signal that is modulated and amplified, enabling the basestation to communicate with mobile devices.
17. The system of claim 13 , wherein the modulator compensation parameter is configured to change at least one of a phase and gain characteristic of the input signal to compensate for an imbalance induced by the modulator.
In the signal transmission system described in claim 13, the modulator compensation parameter modifies either the phase, the gain characteristics, or both of the input signal. This adjustment is done to compensate for imbalances caused by the modulator. By manipulating the phase and gain of the input signal, the controller can effectively counteract modulator-induced errors, leading to a cleaner output signal.
18. A method comprising: generating, by a controller, a modulator compensation parameter based on a modulated feedback signal corresponding to an output signal of a modulator, the modulated feedback signal being a portion of the output signal of the modulator and being coupled to the controller; and generating a power amplifier predistortion signal based on an amplified feedback signal corresponding to an output signal of a power amplifier, the power amplifier coupled to the modulator and configured to receive the output signal of the modulator, the amplified feedback signal being a portion of the output signal of the power amplifier and being coupled to the controller, wherein the modulated feedback signal is different from the amplified feedback signal.
A method for signal correction involves generating a modulator compensation parameter based on a feedback signal from the modulator’s output, and a power amplifier predistortion signal based on a separate feedback signal from the power amplifier’s output. The modulator compensation parameter corrects errors introduced by the modulator, while the power amplifier predistortion signal corrects errors introduced by the power amplifier. These two feedback signals are distinct, allowing independent correction of each component.
19. The method of claim 18 , further comprising: generating an input signal for the modulator, wherein an operational characteristic of the input signal is changed based on at least one of: the modulator compensation parameter and the power amplifier predistortion signal.
The signal correction method described in claim 18 includes generating an input signal for the modulator. The characteristics of this input signal are changed based on the modulator compensation parameter and/or the power amplifier predistortion signal. This adjustment pre-corrects the signal before it enters the modulator and power amplifier, compensating for their known imperfections and leading to a cleaner output.
20. The method of claim 19 , wherein an effect of a change to the operational characteristic of the input signal based on the modulator compensation parameter is substantially cancelled by the modulator while the modulator is modulating the input signal.
In the signal correction method described in claim 19, any changes made to the input signal's characteristics based on the modulator compensation parameter are effectively cancelled out by the modulator itself during the modulation process. This pre-correction ensures that the signal leaving the modulator is as clean and accurate as possible, despite any inherent imperfections in the modulator's operation.
21. The method of claim 19 , wherein an effect of the power amplifier predistortion signal on the amplified signal is substantially cancelled by the power amplifier while the power amplifier is amplifying the output signal of the modulator.
In the signal correction method described in claim 19, any distortion effects introduced by the power amplifier predistortion signal on the amplified signal are effectively cancelled out by the power amplifier during amplification. The power amplifier is therefore configured to remove distortions from the signal it amplifies, resulting in a cleaner and more accurate output signal.
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October 17, 2014
August 1, 2017
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